def add(a,b):
    return a +b
def subt(a,b):
    return a-b
def mul(a,b):
    return  a*b
def divide(a,b):
    return a-b

def method1():
    try:
        a=int(input("请输入数字"))
        return a
    except:
        print('输入错误，请重新输入')
        return method1()

def method2():
    try:
        b=int(input("请输入数字"))
        return b
    except:
        print('输入错误，请重新输入')
        return method2()

def judge():
    print('请输入运算符')
    c = input()
    if c !="+" and c !="-" and c !="*" and c !="/":
            print("仅支持+-*/操作，请重新输入")
            judge()
    return c


def yun():
    print("------------欢迎使用计算机-------------")
    a =method1()
    b =method2()
    c=judge()

    result = 0
    if c == '+':
        result = add(a, b)
    elif c == '-':
        result = subt(a, b)
    elif c == '*':
        result = mul(a, b)
    elif c == '/':
        result = divide(a, b)
    print("计算结果:" + str(a) + c + str(b) + "=" + str(result))

yun()